The invention relates to cartons and, more particularly to closure mechanisms for folding cartons. As used herein, a xe2x80x9ccartonxe2x80x9d is a type of container which is formed of a substantially rigid, inextensible (substantially non-plastic or non-flexible) material such as xe2x80x9ccarton boardxe2x80x9d which is cut and folded to form a substantially three-dimensional structure which has the form of a rectangular prism having a length (or height), a width and a depth. A piece of carton board which has been cut and otherwise formed for use as a carton is referred to herein as a xe2x80x9ccarton blankxe2x80x9d. (A carton blank is also sometimes referred to as a xe2x80x9cformed blankxe2x80x9d.) The cutting and forming of a piece of carton board typically involves die cutting. As used herein, xe2x80x9cdie cuttingxe2x80x9d refers to the process of cutting a sheet of material into a shape suitable for assembly into a carton.
As used herein, xe2x80x9ccarton boardxe2x80x9d is a heavy weight, sheet of paper or other fiber substance including paperboard, cardboard, fiberboard, containerboard, tagboard and corrugated board. The following materials are also known for use as carton board:
Solid Bleached Sulfate (SBS) is a premium grade of folding carton board, which is a solid sheet of paperboard manufactured from bleached kraft pulp, and which is generally clay-coated on one side.
Clay-Coated Recycled Boxboard (CRB): A key paperboard grade for folding cartons. CRB is made from recycled materialxe2x80x94mainly, old newsprint and old corrugated containersxe2x80x94and coated with a layer of clay to provide a smooth white surface for packaging graphics.
Uncoated Recycled Board (URB): Uncoated paperboard grades manufactured primarily from old newsprint and old corrugated and used in both folding cartons and in the manufacture of paper tubes and cores. URB is typically made on cylinder machines and often referred to generically as cylinderboard.
As used herein, xe2x80x9cpaperboardxe2x80x9d is a term used to describe a material which comprises laminated layers of paper. As used herein, xe2x80x9cpaperxe2x80x9d is a general term used to describe sheets of intertwined plant fiber. Synthetic papers from mineral, animal, or synthetic materials can also be made. Paper and paperboard are non-specific terms which could be applied to either form. Paperboards used in packaging generally have a thickness between 0.010 and 0.024 inches (0.25-0.60 mm).
The present invention relates to folding cartons. As used herein, a xe2x80x9cfolding cartonxe2x80x9d refers to a general class of container which is distinct from either a rigid box or case. As discussed in greater detail hereinbelow, it is also distinct from a bag or envelope. The folding carton is typically a plain or printed container of paperboard, including both single and multi-layer paperboard, which is delivered either flat or folded, glued, and collapsed, to be erected, filled, and closed by the user. Folding cartons are designed to protect a product during shipment and on the store shelf, and to enhance the product""s appeal to the consumer. Folding cartons typically feature high-quality graphics to maximize shelf appeal in a retail outlet and to provide information about the product and its use. The market is primarily consumer nondurable goods.
In order to facilitate folding a carton blank into a cartonxe2x80x94in other words, assembling the carton from a carton blank, the carton blanks may also incorporate xe2x80x9ccreasesxe2x80x9d or xe2x80x9cscore linesxe2x80x9d. As used herein, a xe2x80x9cscore linexe2x80x9d is a rupturing of the surface of blank paperboard sheet material, typically resulting in a depression on one side of the sheet and a welt on the other, which facilitates the paperboard blank being folded along that line. As used herein, to xe2x80x9cscorexe2x80x9d a carton (or paperboard) blank is the act of making an impression or partial cut in a flat material for the purpose of facilitating bending, creasing, folding or tearing. A xe2x80x9cfolding scorexe2x80x9d in which the fibers of the carton board are compressed but not cut, helps ensure that a fold or bend takes place along the score line.
Sometimes, slits are formed in the material of the paperboard. As used herein, a xe2x80x9cslitxe2x80x9d comprises a cut which extends completely through the material of the paperboard to separate a one portion (e.g., panel) of the paperboard blank from another portion thereof. Sometimes, perforations are formed in the material of the paperboard. As used herein, a xe2x80x9cperforationxe2x80x9d is a series of slits, typically along a straight or curved line, extending completely through the material of the paperboard, typically for facilitating tearing along the line by a user. A type of xe2x80x9cscorexe2x80x9d which functions much like a xe2x80x9cperforationxe2x80x9d is the xe2x80x9ctearing scorexe2x80x9d, in which the fibers of the carton board are cut approximately halfway through the carton board to permit tearing along the score lines. A tearing score can, of course, also function as a folding score.
A number of closure mechanisms are known for cartons. A one type of pressure-activated closure includes hook and loop material, which is bulky, expensive and difficult to apply automatically.
As described hereinabove, a carton is a type of packaging that uses relatively rigid (inflexible) materials. In contrast thereto, bags and envelopes are a type of xe2x80x9cflexible packagingxe2x80x9d that uses flexible material such as foils, films, paper, plastic films, laminates or sheeting to form a container which, when filled and closed, can be readily changed in shape.
Viewed from another perspective, a carton is a substantially three-dimensional container having a length (or height) H, a width W and a depth D. And, as used herein, the term carton is limited to containers having such dimensions which are substantially on the same order of magnitude (within one-tenth or ten times) each other. For example, a carton may have a depth dimension D of 1.0 inches (2.5 mm), and height H and width W dimensions which are each approximately 5 inches (12.5 mm). In other words, the depth dimension D of a xe2x80x9ccartonxe2x80x9d (as the term is used herein) is a substantial fraction, such as greater than one-tenth of the lesser of the height H and width W dimensions.
Another type of container is the bag or envelope. As used herein, a xe2x80x9cbagxe2x80x9d or an xe2x80x9cenvelopexe2x80x9d is a type of container which is formed of a substantially flexible material, such as lightweight paper or plastic which is generally formed as two rectangular sheets joined along three sides thereof, a one sheet extending beyond the remaining edge of the other sheet and forming a flap which is folded over to close the envelope or bag. The xe2x80x9cthicknessxe2x80x9d of the resulting bag or envelope is substantially zero, considering that there is no distinct top or bottom panel, but rather merely a fold line defining where the flap portion of the panel begins. The sheet typically has a thickness which is less than 0.010 inches or 0.25 millimeters (mm). Whereas a carton is a substantially three-dimensional container, a bag or envelope is a substantially two-dimensional container having no substantial depth dimension. A number of closure mechanisms are known for bags or envelopes.
U.S. Pat. No. 3,079,066 discloses temporary sealing means permitting ready opening and reclosure of a bag (6). A closure flap (10) is provided with at least one opening (11) therethrough. A strip (12) is secured to the outer surface of the closure flap (10) in overlying relation to the openings (11). The strip (12) is provided on one side thereof with an adhesive layer (13) which may be of any tacky, non-permanent type adhesive. The tape (12) is secured to the closure flap (10) by means of the adhesive coating (13). When the closure flap (10) is in its bag-closing position, the strip (12) will have those portions thereof overlying the openings (11) depressed into the openings (11), with the adhesive layer (13) engaging the underlying portion of the body (7) of the bag (6).
U.S. Pat. No. 3,256,941 discloses a reclosable plastic bag (10) which is easily shut without heat-sealing, and which is easily opened without cutting or tearing. A flap (20) is provided with a series of mutually equidistant spaced holes (22). A strip (24) of polyethylene (or paper, or aluminum foil) which has pressure-sensitive adhesive coating (26) on one surface is applied to the rear surface of the flap (20). The adhesive coating (26) binds the strip (24) to the flap (20). To close the bag, the flap is folded and pressed against the front wall of the bag. The plastic bag is described as polyethylene, and various different flexible plastic materials can be used, including cellophane, paper and other traditional bag materials.
Canadian Patent No. 745,888 discloses an envelope having a closure flap which may adhere to the main body of the envelope, be pulled away from the envelope, and adhere again a plurality of times without losing its effectiveness of adherence. An envelope has a closure flap (2). Apertures (3,4,5,6,7,8,9) of different shapes are provided in the flap. An adhesive tape (10), such as the one known by the trademark xe2x80x9cSCOTCH TAPExe2x80x9d, is disposed on the outside surface of the flap, and the adhesive is exposed in the apertures. A peelable strip (11) is disposed on the inside surface of the flap to protectively mask the exposed adhesive, and is peeled off before sealing the flap. The portion of the envelope which will receive the closure flap is provided with a tape (12) having a relatively high glossy surface. When the exposed adhesive of the adhesive tape (10) comes in contact with the glossy surface of the tape (12), a good reliable bond exists, and when the closure flap is pulled away from the tape (12), the glossy surface retains very little or no tacky material from the adhesive tape (10).
It is an object of the invention to provide an improved construction for a folding carton and, more particularly, an improved closure mechanism for a folding carton.
It is another object of the invention to provide a closure mechanism for a folding carton which is low in profile, low cost, and which can readily be applied by automated machinery.
According to the invention, a pressure-sensitive closure mechanism is incorporated into a container which is a carton, preferably a folded carton. The closure mechanism incorporates a pressure-sensitive tape having adhesive on one surface thereof disposed on a one side of a hinged lid panel, with the adhesive exposed through an opening in the lid panel. The adhesive releasable engages an outer surface of a flap-receiving panel.
The carton which is used to illustrate the closure mechanism for this invention has a rectangular body with a hinged lid panels. The lid panel is preferably a double thickness (two plies) of paperboard material. These two plies are formed by folding over an additional inner lid panel, which is connected to an outer lid panel via a score or fold. Both plies of the lid have holes or voids cut into them that line up with each other. Before the lid panel is doubled over, a pressure-sensitive tape (or label) is placed over an opening in the inner lid panel. The lid panels are then doubled over to form one double ply lid. The outer edges of the tape or label are thus hidden from view for a clean appearance. When the lid is closed over the opening in the carton, the user applies pressure with his finger to the backside (non-adhesive) side of the pressure-sensitive tape. The pressure pushes the tape against the adjacent face of the carton. The lid (closure flap) is thus temporarily secured to the carton body. The adhesive on the tape is chosen such that upward force on the lid will break the bond between the tape and the carton face allowing the lid to be opened. Repeated closings and openings are possible.
The pressure-adhesive tape, which is the principal element of the closure mechanism of the present invention, is a relatively flexible element. Although some similar closure mechanisms are known for bags and envelopes, it is not obvious that such closure mechanisms would function well (if at all) on a carton. The flaps of the bags and envelopes are also very flexible. The flap of a carton is relatively inflexible (rigid). As mentioned hereinabove, cartons are quite different from bags or envelopes. A carton is a substantially rigid container, formed of a substantial material (c., at least 0.010 inch thick paperboard), and each of its (typically six) sides has substantial dimensions (within the same order of magnitude as the dimensions of another side). A carton, more particularly an empty carton, can thus readily support and balance itself on any of its sides (e.g., front, back, top, bottom, left, right). This is in marked contrast to a substantially flexible and/or two-dimensional (when empty) bag or envelope.
Other objects, features and advantages of the invention will become apparent in light of the following description thereof.